Trees stand scorched by the Rim Fire in the Stanislaus National Forest along Highway 120 near Yosemite National Park, Monday, Aug. 26, 2013 in, Calif. With winds gusting to 25mph on Sierra, hundreds of firefighters have been deployed to protect this and other communities in the path of the Rim Fire raging north of Yosemite National Park. (AP Photo/The Sacramento Bee, Paul Kitagaki Jr.)

Photo: Paul Kitagaki Jr., Associated Press

Trees stand scorched by the Rim Fire in the Stanislaus National...

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Lack of rain and low humidity have led to a high number of wildfires in Northern California the past two months.

The California Department of Forestry and Fire Protection suspended burn permits in much of the Bay Area on Monday, citing abnormally dry conditions that have led to a sharp increase in vegetation fires.

The state's firefighting agency banned fires on 31 million acres of state property and private land under state jurisdiction in Alameda, Contra Costa, Santa Clara, San Mateo and Santa Cruz counties and parts of Stanislaus and San Joaquin counties.

The suspension began Monday morning and will last indefinitely.

Wildfire fears in the Bay Area are all but unheard of in late December, but this is not a normal year. Calendar-year rainfall totals will set record lows in many locations, and persistent low humidity and high levels of dry fuel have led to an unusual number of fires, including this month's wildfire in Big Sur, Cal Fire officials said.

In Santa Cruz County alone, there have been 31 vegetation fires in November and December, authorities said. Normally, there would be five to seven such fires. About half the blazes have been caused by people burning debris.

Campfires are still allowed in campgrounds or on private property with the landowner's permission, as long as there is no chance of nearby vegetation catching fire, officials said.

There is no sign of a change in the weather that could ease the fire danger. The National Weather Service says no storms are likely to hit Northern California for at least a week, thanks to an all-but-immobile high-pressure system that is deflecting systems well to the north.

The stagnant high-pressure system also affects air quality. The Bay Area Air Quality Management District called for the winter season's 23rd Spare the Air alert on Tuesday, which means Bay Area residents aren't permitted to light wood fires for 24 hours.